[Pw_forum] difference between DFT+U+J and rotational invariant DFT+U of lda_u_kind =1

[Jia Chen]

Dear all,

I am working on molecule with localized d electrons and two different spin
states, especially correlation due to Hund's coupling J at this moment. I
tried the DFT+U+J method (PRB 84, 115108, 2011) implemented in Quantum
Espresso, and found out the J dependence is quite different from the
rotational invariant DFT+U (PRB 52 R5467, 1995).

I am surprised by the results, because rotational invariant DFT+U has full
coulomb interaction parametrized by Slater integrals, Hund's coupling J
show up in anisotropic and spin polarized interactions. As a model, it
covers both Hund's first and second rule. Theoretically, I don't know
what's missing in this method.

Apparently, developers of DFT+U+J know how to go beyond rotational
invariant DFT+U. I read the paper, but still don't understand the idea
behind it. I would like to ask two questions:
1. What is not right in rotational invariant DFT+U, as a Hartree-Fock level
theory regarding J?
2. How DFT+U+J improves rotational invariant DFT+U, just in general?

Appreciate your help!

Cheers
-- 
Jia Chen
Postdoc, Columbia University
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20140317/eb956b17/attachment.html>